I was recently sparring lightly with a friend of mine, having not sparred for months having worked on my jiu-jitsu. To my shock I've noticed that I can't keep my hands up - when they were about to go for mid-kicks I would lower my hands to block/grab, and even worse, would keep it down there even when they were just feinting. I've had this problem before - originally I was practicing Taekwondo, which had you lower your hands to block. However, I started learning boxing and to keep my hands up, chin down, and above all, don't leave my hands down to try and grab but rather block with my arms. I know that if I were against a muay thai fighter that they would be able to probably level me with a high kick because I would drop my hands to block a kick that wouldn't be there. Does anyone have any recommended ways to help me out and make me break the habit?